Hi Guarana,
Does the upset stomach occur after you take a pill and how long does it last? Did you mean 0.3% hyperforin? Have you tried Perika? It's standardized to 2% hyperforin and has vitamin C added to stabilize the hyperforin.
Also, are you taking it after a meal or on an empty stomach? Ginkgo is actually weak and may or may not give you any noticeable effects. It's primarily a norepinephrine reuptake inhibitor so if it works you can expect an increase in energy, focus, motivation, and possibly mood. However, hyperforin is also norepinephrine reuptake inhibitor and a serotonin, dopamine, and GABA reuptake inhibitor. So SJW would most likely cancel out any effects that ginkgo may have.